Show a compact year-less date in the day bar so it fits small iPhones

The native date input can't be told to drop the year, so a button face
shows e.g. "Jul 10" and the real input sits hidden behind it, still
holding the value and opening the native picker on tap.

src/index.html

@@ -86,7 +86,13 @@
           <span id="bar-clock-time"></span>
         </div>
         <button type="button" id="day-prev" class="ghost" aria-label="Previous day">←</button>
-        <input type="date" id="day-picker" />
+        <!-- A browser won't let us shorten the text a native date input shows,
+             so the face button carries a compact year-less date and the real
+             input stays (visually hidden) as the value + native picker. -->
+        <span class="day-date">
+          <button type="button" id="day-date-face" class="ghost"></button>
+          <input type="date" id="day-picker" tabindex="-1" aria-hidden="true" />
+        </span>
         <button type="button" id="day-next" class="ghost" aria-label="Next day">→</button>
         <button type="button" id="day-today" class="ghost">Today</button>
       </section>